Direct determination of trace elements in niobium, tantalum and their oxides by inductively coupled plasma atomic emission spectrometry after microwave dissolution

Analytical schemes for the determination of trace elements in high-purity niobium, tantalum and their oxides are proposed. The schemes are based on microwave dissolution of the metals and oxides followed by inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of impurities in the solutions. The possibilities of interelement and off-peak background corrections in ICP-AES analysis are discussed. The accuracy of the results obtained is confirmed by the determination of trace elements after a matrix sorption separation procedure. For a number of elements, a comparison of the results obtained by ICP-AES without and with the matrix separation procedure and by electrothermal atomic absorption spectrometry (ETAAS) shows good agreement. The limits of detection for direct ICP-AES determination are in the range 0.4-1.0 μg g-1 for Ba, Ca, Fe, Mg, Mn, Y and La; between 2.0 and 10.0 μg g-1 for B, Cd, Co, Cr, Cu, Hf, Mo, Na, Nb, Ni, Pb, S, Ti, Zr and Ta; and for K, Sb and W a detection limit of 20 μg g-1 is achieved. The schemes proposed are intended for rapid routine analysis.